¹L.G. Vacher, ¹J. Eschrig, ¹L. Bonal, ²W. Fujiya, ¹L. Flandinet,¹P. Beck
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2024.12.016]
¹Institut de Planétologie et d’Astrophysique de Grenoble, Université Grenoble Alpes, CNRS CNES, 38000 Grenoble, France
²Faculty of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, 310-8512 Ibaraki, Japan
Copyright Elsevier

Non-carbonaceous (NC) meteorites, such as enstatite and ordinary chondrites, are regarded as potential building blocks of terrestrial planets, possibly delivering volatile elements to the inner solar system. However, their parent bodies underwent intense thermal metamorphism during planet formation, raising questions about whether planets accreted volatile-rich or volatile-poor materials. Ordinary chondrites-like materials may have contributed significantly to the formation of Mars, but the impact of thermal metamorphism on their initial volatile content and isotopic composition is unclear. This study reports the bulk-rock hydrogen, carbon, and nitrogen abundances and isotopic compositions (δD, δ13C, δ15N) of unequilibrated ordinary chondrites (UOCs) across petrologic subtypes (PT) 3.00 to 3.9. Upon removing terrestrially contaminated samples, we found that the matrix-normalized hydrogen, carbon, and nitrogen concentrations are inversely correlated with the Raman spectral parameters (FWHMD), a tracer of thermal metamorphism in type 3 chondrites. Only δD shows a correlation with FWHMD, suggesting that δ13C and δ15N were not fractionated despite carbon and nitrogen being outgassed from the interior of the planetesimal. With increasing metamorphism, we proposed that less-metamorphosed UOCs (PT < 3.2) progressively lost deuterium (D) due to the breakdown of D-rich phyllosilicates above 300 °C, as supported by our FTIR analyses. We conducted thermal modeling to better understand how thermal metamorphism influences the delivery of water to terrestrial planets. Our results suggest that UOC-like precursors did not significantly contribute to Mars’ accretion due to the rapid progression of thermal metamorphism within ordinary chondrite planetesimals. However, volatile-rich UOCs may have supplied most of the hydrogen to Mars, implying that Mars’ primitive mantle may have recorded and retained a strong D-rich reservoir in its interior.

¹Dominik C. Hezel,²Kerstin A. Lehnert,³Premkumar Elangovan,²Peng Ji,²Jennifer Mays,⁴Jörn Koblitz
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14293]
¹Goethe-Universität Frankfurt, Institut für Geowissenschaften, Frankfurt am Main, Germany
²Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York, USA
³Astute Digital Solutions Ltd., Guildford, UK
⁴Schulstr. 18A, 27721 Ritterhude, Germany
Published by arrangement with John Wiley & Sons

MetBase has been the world’s largest database for meteorite compositions, but has now passed this torch on to the Astromaterials Data System (Astromat), into which MetBase has recently been merged. This merger had been planned for some time and took almost 1 year to complete. Not only differences in the structure of the databases, in the content and organization of data and metadata, and in the terminology used but also incorporation of new data needed to be resolved to combine the data holdings of MetBase with the Astromat synthesis database. Astromat is NASA’s primary archive for laboratory analyses of astromaterial samples and funded by NASA to provide services for the preservation and open access of data from astromaterials, including meteorites, in alignment with the FAIR principles. After merging MetBase into Astromat’s synthesis database, this now provides the cosmochemical community the largest compilation of cosmochemical analytical data by far: over 2 million analytical data points. Astromat is also part of a bigger ecosystem of geo- and cosmochemcial databases, as its foundation is aligned with other large geochemical databases such as EarthChem and GEOROC. The visualization tools and the teaching tool from MetBase will be further developed and now exist as independent tools. We provide a brief history of the two databases and their journeys, an outlook toward the future, as well as lessons learned from this merger. We recommend that other cosmochemical databases try whenever possible to adopt the Astromat database schema as early as possible, or get in contact for alternative options. We believe MetBase now being a part of Astromat is a match made in heaven and hope Astromat will become a reliable and trusted service within the community.